Hmmm...
I'm fairly new to animation (I'm still studying the principles and not really animating much >>; ), so my crit may not be very good ^^; I'll try my best, though!
Before saying anything, I think it's great you're aiming for animated cutscenes! Seriously, I wish I had the patience to do that kind of thing @_@ Animating is so much work
So I wish you the best!

The animation looks nice as it is, btw, I quite like it! But yes, it could be improved and made more dramatic.
Now, let's see if I can help...
You have two actions: girl releasing herself from the guy's embrace and girl hitting the guy.
I think you need to exaggerate the anticipations and reactions a bit more to make them more dramatic.
On the first action, there's not much anticipation on her breaking the embrace. I think a couple of frames with her getting closer to the guy while raising her arms, lowering her head a bit and moving her elbows backwards to take impulse to shove the guy off would work. Also the reaction of the guy, staggering a tad to a more unstable/caught by surprise position after she shoves him off would be nice, possibly with him having his arms less relaxed and close to his body.
On the second action, she naturally moves her hand from being on the guy's chest to the ready-to-slap position. I'd add a bit more anticipation there, maybe making the hand draw a circle, going a bit down than its current position and then up. I'd also exaggerate that pose, to make the slap seem more strong (right now the slap doesn't feel very strong), and make her use more of the force of her body than just the force of his hand and arm as it seems right now.
I agree that, with clothes and hair you can emphasize more the action, with secondary animation of them. It'd be nice, specially for the guy's reaction close-up, that right now just looks like a frozen frame.
I'd expect him, after the frozen shock moment to move the head a bit down (in anticipation) and then up again to look at the girl while raising her hand to the hurt cheek.
I hope all the blabbery made some sense @_@
Keep up the good work!!
